When Michelle Obama spoke before the Democratic national convention four years ago, her self-description as America’s “mom-in-chief” made many white feminists squirm. Those critiques glossed over race and in particular, that having a black woman in the White House – to say nothing of a whip-smart, strong, professionally accomplished black woman in the White House – is nothing short of revolutionary.

But in her thunderbolt of a speech on Monday night, Michelle Obama didn’t let America forget where she came from, or how far the country had come, and how those storylines relate to one another in embracing her role as a mother and a leader.

“That is the story of this country,” she said. “The is the story that has brought me to this stage tonight. The story of generations of people who felt the lash of bondage, the shame of servitude, the sting of segregation, but who kept on striving and hoping and doing what needed to be done – so that today I wake up every morning in a house that was built by slaves.”

‘It was spectacular’

The speech alluded to Republican nominee Donald Trump, but it also drove home the profundity of all she personally had achieved just by virtue of standing where she was, there on the stage of the DNC encircled by star-shaped lights and thronged by thousands of adoring Americans.

“It was spectacular,” said Bob Shrum, a Democratic consultant and strategist. “It had the gift of all really great speeches: authenticity. It wasn’t manufactured or pre-cooked. It had a wonderful narrative line.”

Delegates stood and cheered as the first lady delivered her speech on the first day of the Democratic national convention. Photograph: Chip Somodevilla/Getty Images

Obama did not mention Trump by name. But Anita McBride, former chief-of-staff to first lady Laura Bush, described the address as unusually politically charged for first ladies in general and Obama in particular. She said: “Of all the speeches I’ve seen her do, this was by far the most political. She has a clear view of how high the stakes are for the legacy of her husband.

“After eight years starting as a political novice, she has come full circle to a recognition of how important her voice is in the process. Most importantly, she’s a far cry from her first public statement [in 2008] that got such attention – ‘for the first time in my adult lifetime I’m really proud of my country’ – to saying this ‘is the greatest country on earth’. It’s been an education for her over eight years of what the country represents.”

Asked how Obama would be remembered, McBride, now executive-in-residence at the Center for Congressional and Presidential Studies at American University in Washington, said: “She’s taken advantage of the platform and put her personal stamp on it and followed her path while not compromising her personal life of family. She found her voice and used it the way she felt best.”

‘Nurturer-in-chief’

In the rapturously received speech, Obama outlined parallels between parenting and the presidency. Joshua Kendall, author of First Dads: Parenting and Politics from George Washington to Barack Obama, said: “Donald Trump can show off his kids, and they’re reasonably articulate, but the one thing that’s really missing is a vision of the future and what we’re going to leave our children. That’s what came through her speech: looking through the eyes of her daughters.

“She’s very aware that kids see her as a mother so she chooses her words carefully, drawing a contrast with Trump who uses language carelessly.”

Kendall added: “She and Hillary Clinton have had a frosty relationship. In 2008 it was kind of tough. The subtext from this is that like many Americans she’s really scared of Trump. It was a very passionate speech and whatever conflicts she’d had with Hillary, she’s putting that in the past.”

Back in 2008, Kendall said, Obama’s popularity was down at 22%. “People saw her as an ‘angry black woman’. But now she’s carved out this turf as nurturer-in-chief. People can see that her campaigns, like for children’s nutrition, really come from the heart.”

Political legacy

Michelle Obama’s political legacy is not just a laundry list of everything she has spearheaded politically, from the “Let’s Move!” campaign to her lectures on parenting, and how to raise happy and healthy kids. It’s something that cuts to the core of her identity.

She is only the fourth first lady (after Pat Nixon, Hillary Clinton and Laura Bush) to achieve a postgraduate degree, and back when she was a lawyer at the Chicago firm Sidley Austin it was she who mentored Barack Obama, not the other way around.

In her address to the convention, Michelle Obama tackled race, politics and parenting head on. Photograph: Jim Watson/AFP/Getty Images

When she talks about motherhood, it casts the flexibility to choose motherhood not as the role into which women are forced into over a career, but as the privilege it is.

But what was perhaps more impressive was the singularity with which she appreciates the role Clinton has carved out even as she has gone in a different direction: after she leaves the White House she will return to her personal life and career, eschewing politics.

But her speech on Monday night illustrated the new frontiers she might go on to pave for black women in power, and as such it underscored more than ever the loss of what could be politically.

Obama often gets compared to Clinton, who as first lady once said: “I am not some Tammy Wynette standing by my man,” and, “I suppose I could have stayed home and baked cookies and had teas, but what I decided to do was to fulfill my profession which I entered before my husband was in public life.” But Michelle Obama has had a harder road to tread.

She is not just a fiercely accomplished, powerful woman remaking her identity as a woman in the White House – she is all of that and African American.

She is also uniquely qualified to appreciate the struggles Clinton has had to deal with both during her time as first lady, and as a presidential candidate – and perhaps also to illustrate how surprising it is that a former first lady such as Clinton has gone through the fire of press and political scrutiny in that role and then chosen to run for president at all.

This article was amended on 27 July 2016. A previous version incorrectly cited Obama as the second first lady who had earned a postgraduate degree; she was the fourth.